In the cigarette making art, there is a tendency for small particles or strips of tobacco to fall out of the ends of tobacco rods ("loose ends") during the handling, packaging and shipping associated with the manufacture of production cigarettes, and during handling by retailers and distributors as well as by the consumer. In fact, the loss of tobacco resulting from such loose ends has been measured to exceed 16% on a weight-based average. One method for minimizing loose ends requires the introduction of an additional quantity of tobacco in the cigarette filler stream at predetermined spaced intervals along the longitudinal extent of the nascent tobacco rod. An adhesive is applied to a longitudinal edge of the cigarette wrapping paper into which the stream of tobacco filler is deposited, the cigarette paper then being wrapped about the tobacco filler with the adhesive-applied edge overlapping the opposite paper edge and containing the tobacco filler in a continuous rod-like shape. The resulting increased density of tobacco filler located at those predetermined spaced intervals coincides with the tobacco rod ends after cutting into individual tobacco rods during cigarette production. Each of the tobacco rod ends on either side of the cuts has an increased packing density of tobacco known as a "dense end." Such dense ends tend to reduce the undesired loss of tobacco during handling of the tobacco rod during manufacture and subsequent handling of the cigarettes.
While this provides an acceptable solution to the "loose end" problem, the value of this approach is compromised from a cost standpoint by reason of the requirement for additional tobacco to create the dense end. It is also known that a dense end of a tobacco rod in which the tobacco is overly compacted will restrict the flow rate of tobacco smoke through the cigarette when used as intended, thereby undesirably increasing the draw resistance encountered by the smoker at the beginning of the smoke and giving the smoker the perception of a poor or inconsistent product.
Various other approaches have been taken to reduce loose ends in tobacco rods. U.K. Patent Application No. 2 243 983, for example, discloses a method and apparatus for forming a cigarette having adhesive applied in strips by a print wheel along one longitudinal edge of the wrapping paper and at spaced longitudinal locations across the entire transverse dimension of the paper from that edge. The cigarette paper is then wrapped about the stream of tobacco filler deposited thereon and the longitudinal adhesive strip is secured to the opposite edge of the paper. Each transverse adhesive strip forms an adhesive annulus about the entire inner circumference of the formed tobacco rod. The tobacco rod is then transversely cut at the midpoint of each transverse adhesive strip and at the midpoints between the strips to form tobacco rods with an annular adhesive band at the inner surface of the free end of each tobacco rod to prevent "loose ends."
According to an alternative embodiment of the apparatus, the adhesive is applied to the cigarette paper by a blast of air which is directed against a screen carrying a liquid adhesive to cause the adhesive to be thrown against the cigarette paper. A shaft-mounted disk rotating at a predetermined speed in synchronization with the advancing cigarette paper includes a window through which the air blast is directed at those time intervals corresponding to the rotational speed of the disk. An important problem with this arrangement is overspray inherent in the operation of this apparatus, thereby limiting precise and uniform application of the adhesive to the cigarette paper. Another problem is the relatively limited speed of tobacco rod production based on a relatively slow rotational speed of the disk, that speed being necessarily limited to enable the passage of a blast of air through the disk window where it impinges on the adhesive-carrying screen and ejects the adhesive therefrom onto the cigarette paper.
U.S. Pat. Nos. 4,715,388 and 4,785,831 disclose other methods and apparatus for minimizing the loose ends of cigarettes, for instance, by incorporating into the tobacco filler a hygroscopic powder that becomes tacky upon absorption of moisture or by applying a foamed adhesive to the free ends of the cigarettes after manufacture. The latter method and apparatus suffer from similar deficiencies as other prior art apparatus in that it is not capable of operating at the high production rates associated with modern cigarette making machinery. The former method creates the possibility of undesirably staining the cigarette paper with powder particles that contact that paper.
In view of the foregoing deficiencies of the prior art methods and apparatus, it would be desirable to provide a method of and an apparatus for minimizing loose ends of cigarettes that is capable of operating at the production speeds of modern cigarette manufacturing machinery. In particular, it would be desirable to provide a method of and apparatus for minimizing loose ends of cigarettes that is capable of being used during the cigarettes manufacturing process on existing machines capable of production speeds of 8000 cigarettes or more per minute.